Conventional SEPIC converters include an oscillator with respective components operating at a given frequency, possibly modulated via additional circuits.
In various solutions it is possible to realize the converter with a monolithic chip and/or by means of an integrated controller capable of implementing the oscillator, the pulse-width modulation (PWM) modulator, the output driver circuit and, possibly, the current loop system and/or an error amplifier for output voltage regulation.
In such application context the need arises of having converter circuits capable of dispensing with a dedicated oscillator and/or a specialized chip, with the possibility of employing a SEPIC topology within the framework of a self-oscillating converter including conventional active parts, such as e.g. transistors and diodes. This in order to provide an efficient structure, with a reduced number of parts and with a subsequent reduction of costs, e.g. to provide an application suitable converter in low power supplies, with a wide range of input values and a constant output voltage.
To this regard, it has been noted that integrated circuits may result unsuitable for such purposes when considering the incompatibility between their technology and the wide range of input values requested for a SEPIC application, primary aimed at generating an output voltage higher or lower than the input voltage.
To this regard, the following has also been noted:                self-oscillating solutions have already been applied to a SEPIC topology (e.g. to produce so-called ballast or power factor correction stages) in power applications and by using specific inductors brought to saturation and/or employing a specific driving winding coupled to a power inductor to sustain (self)oscillation, and        in such a solution, the working frequency may turn out to be variable as a function of the load and input voltage, as opposed to what might happen in converters provided with an oscillator, whose working frequency is normally fixed.        
The need therefore is felt for converter circuits capable of dispensing with special (customized) inductive components with the possibility of replacing such components with active parts which may be both smaller and cheaper.